just got the tranny back from Penn Detroit Diesel for the installation of alto clutches, transgo, and suncoast converter. truck will slam into reverse and when put in any forward gear the 3rd light will blink and not go into any gear.
what could be wrong? when i say slam into reverse i mean it takes all the brakes have to hold it from chirping the tires. i'm totally disgusted with this and dont know what to do. penn doesnt open until monday and was looking for some help.

I am no tranny expert but maybe a misadjusted NSBU switch.......

PM MikeL. he will give you some help .........

Good Luck,

T:cool: NY

not new to the performace world but new to the allison tranny, what is the nsbu switch and what does it do?

not new to the performace world but new to the allison tranny, what is the nsbu switch and what does it do?
Alot.

Formerly called a nuetral switch, this switch tells the TCM (trans computer) what gear you are in so that it can send proper signals to the transmission. Example: if switch is malfunctioning and the TCM gets an erronious signal that the Ally is in the nuetral position, then the mainline pressure to the clutches will be cut back and cause slip. The opposite can also happen and cause high pressure at the wrong time.( This will cause clunks and harsh applys). There almost always is a code stored when this happens ( check engine light).
mike